Rogers G W, Banos G, Nielsen U S, Philipsson J
Department of Dairy and Animal Science, Pennsylvania State University, University Park 16802, USA.
J Dairy Sci. 1998 May;81(5):1445-53. doi: 10.3168/jds.s0022-0302(98)75708-x.
Sire genetic evaluations for protein yield, somatic cell score (SCS), productive life, and udder type traits from the US were correlated with sire evaluations for udder health from Denmark and Sweden and then the correlations were adjusted for accuracies to approximate genetic correlations. Traits from Denmark and Sweden included somatic cell count (SCC) and clinical mastitis from single-trait analyses. In addition, evaluations for clinical mastitis from Denmark and Sweden were regressed on US traits to test for quadratic relationships. Information from 85 bulls with US and Danish evaluations (77 with US type) and from 80 bulls with US and Swedish evaluations (79 with US type) was used to calculate correlations. Genetic correlations of US protein yield with Danish and Swedish SCC and clinical mastitis were all unfavorable (-0.09 to -0.32). Genetic correlations of US productive life with Danish and Swedish SCC and clinical mastitis were all favorable (0.06 to 0.59). Genetic correlations between US SCS and Danish SCC and between US SCS and Swedish SCC were -0.87 and -0.99, respectively (favorable). Genetic correlations between US SCS and Danish clinical mastitis and between US SCS and Swedish clinical mastitis were -0.66 and -0.49, respectively (favorable). The US type traits that had the largest correlations with clinical mastitis from Denmark and Sweden, respectively, were udder composite (0.26, 0.47), udder depth (0.45, 0.52), and fore udder attachment (0.31, 0.34). In general, quadratic regressions indicated little nonlinearity between clinical mastitis and the US traits. Specifically, the US bulls with the lowest predicted transmitting abilities for SCS had the most favorable rates of daughter clinical mastitis in Denmark and Sweden. Selection for increased productive life, lower SCS, and more shallow udders should improve mastitis resistance.
美国种公牛蛋白质产量、体细胞评分（SCS）、生产寿命和乳房类型性状的遗传评估与丹麦和瑞典种公牛乳房健康的评估进行了相关性分析，然后根据准确性对相关性进行调整以近似遗传相关性。丹麦和瑞典的性状包括单性状分析中的体细胞计数（SCC）和临床乳腺炎。此外，将丹麦和瑞典临床乳腺炎的评估结果对美国性状进行回归分析以检验二次关系。利用85头具有美国和丹麦评估结果的公牛（77头具有美国类型）以及80头具有美国和瑞典评估结果的公牛（79头具有美国类型）的信息来计算相关性。美国蛋白质产量与丹麦和瑞典SCC以及临床乳腺炎的遗传相关性均为不利（-0.09至-0.32）。美国生产寿命与丹麦和瑞典SCC以及临床乳腺炎的遗传相关性均为有利（0.06至0.59）。美国SCS与丹麦SCC以及美国SCS与瑞典SCC之间的遗传相关性分别为-0.87和-0.99（有利）。美国SCS与丹麦临床乳腺炎以及美国SCS与瑞典临床乳腺炎之间的遗传相关性分别为-0.66和-0.49（有利）。与丹麦和瑞典临床乳腺炎相关性最大的美国类型性状分别是乳房综合评分（0.26，0.47）、乳房深度（0.45，0.52）和前乳房附着（0.31，0.34）。总体而言，二次回归表明临床乳腺炎与美国性状之间几乎不存在非线性关系。具体而言，美国种公牛中SCS预测传递能力最低的，其女儿在丹麦和瑞典的临床乳腺炎发病率最有利。选择提高生产寿命、降低SCS以及乳房更浅的种公牛应能提高抗乳腺炎能力。
